The present invention relates to a shutting apparatus, and more particularly, to a controller for stopping a motor that drives a shutting apparatus when an obstacle causes an overload to be applied to a shutting apparatus.
A shutter driven by an electric motor typically includes a slat curtain and a spool about which the slat curtain is wound. The motor rotates the spool to wind the slat curtain and raise the shutter or to unwind the slat curtain from the spool and lower the shutter. The rotating speed of the drive motor (current speed) is compared with a predetermined rotating speed (reference speed). If the difference in rotating speed is not within a predetermined range, the motor is stopped.
However, the weight of the unwound portion of the slat curtain changes as it moves. Further, the speed of the slat curtain movement gradually varies as time passes by. Therefore, the load applied to the motor differs as the slat curtain is unwound from the spool. To balance the weight of the slat curtain so that the load applied to the motor is uniform, the spool may be provided with a balance spring. However, it is difficult to maintain the same load throughout the entire moving range of the slat curtain with the balance spring. Furthermore, the load applied to the motor may differ greatly over time for any given position of the slat curtain. Thus, the motor may not be controlled in the desired manner if the same conditions are used to stop the motor. For example, operation of the shutter may be interrupted by a slight load. On the other hand, the shutter may keep operating even when an obstacle causes an overload to be applied the motor.
It is an object of the present invention to provide a controller for a shutting apparatus that smoothly stops a motor that drives a shutting member.
To achieve the above object, the present invention provides a shutting apparatus. The shutting apparatus includes a shutting member that is opened and closed in predetermined directions and a drive mechanism for moving the shutting member in an opening direction and a closing direction between an opened position and a closed position. A plurality of location ranges is defined between the opened position and the closed position. A controller detects the current speed of the drive mechanism in each range, compares a predetermined reference speed and the current speed, and generates a stop signal based on the comparison result to stop the operation of the drive mechanism.
A further aspect of the present invention provides a shutting apparatus. The shutting apparatus includes a shutting member that is opened and closed in predetermined directions, a drive mechanism for moving the shutting member in an opening direction and a closing direction between an opened position and a closed position, and a transmission train arranged between the drive mechanism and the shutting member. The transmission train includes a first output unit. A position detector is located in the transmission train to detect the position of the shutting member and to generate a position detection signal. A second output unit is connected to the drive mechanism. A speed detector is included in the second output unit to detect the speed of the second output unit and to generate a speed signal. A location range memory stores positions of the shutting member in association with a plurality of location ranges defined between the opened position and the closed position in accordance with the position detection signal from the position detector. An output computation device computes the speed of the second output unit from the speed signal of the speed detector. An output memory stores a reference speed of the second output unit for each location range. A processor compares the reference speed with the computed speed of the second output unit for each location range and generates a stop signal based on the comparison result to stop operation of the drive mechanism.
Another aspect of the present invention provides a method for controlling a shutting apparatus. The shutting apparatus includes a shutting member that is opened and closed in predetermined directions and a drive mechanism for moving the shutting member in an opening direction and a closing direction between an opened position and a closed position. The method includes defining a plurality of location ranges between the opened position and the closed position, detecting the speed of the drive mechanism in each location range, comparing a predetermined reference speed and the detected speed for each location range, and generating a stop signal based on the comparison result to stop the operation of the drive mechanism.